Prepare a tray or large platter and line with a cookie sheet or wax paper and arrange watermelon slices, leaving space between each piece. Freeze for 1 hour. After watermelon is frozen you can add to ziplock bag for future use.

Place frozen watermelon pieces in blender, add remaining ingredients and blend until smooth.

Serve immediately. Garnish with a piece of watermelon or fresh mint, if desired. Enjoy!